


We're not so different, you and i

by Hirsutene



Category: Assassination Classroom
Genre: Adoption, Alternate Universe - Canon Divergence, Child Abuse, Fluff, Gen, Hurt/Comfort, Implied/Referenced Child Abuse, Non-Graphic Violence, Protectiveness
Language: English
Status: In-Progress
Published: 2021-03-14
Updated: 2021-03-14
Packaged: 2021-03-17 11:15:39
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 1,938
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/29965548
Author URL: https://archiveofourown.org/users/Hirsutene/pseuds/Hirsutene
Summary: Korosensei never planned on being a father once in his life. Especially not in the current situation.Or: Korosensei finds the family he never had in Nagisa
Relationships: Korosensei & Shiota Nagisa
Comments: 2
Kudos: 12





	We're not so different, you and i

The love of a family was something precious within this world. Many kids were lucky to receive that love, while others weren't so lucky. When he was human, Korosensei was such a child. Abandoned by his parents at a young age, sold into slavery. Growing up in a world without trust or kindness; the child grew up seeing nothing but death and destruction. That became the only thing he'd believe in. He became the best assassin in the country, and never looked back. 

That was until he met her.

She knew everything he'd done. The blood he'd spilled. Yet she still treated him with kindness; the kindness he'd lacked from anyone else his entire life. He'd grown up as an assassin, hating the world. He'd used his talents to kill, and to destroy.. But because of her, he'd finally realized that he could have used these talents for other things.. To help others, not hurt them.

And even after he had changed and been responsible for her death, she still saw something in him. She'd asked him to take care of her students. These children he was destined to love.. The last thing she'd told him in her final breath, was that she was sure he'd make a fine teacher.

He'd made his promise. When his tentacles asked him who he wanted to be, he'd tell them. _'I want to be weak. To be riddled with weaknesses.. I want to be a creature that appears vulnerable. Approachable. I want to be able to perceive the weak. To protect them, to guide them.'_

\------ 

Nagisa Shiota was a strange child, from the moment Korosensei had met him. The child, who had long blue hair tied up in two twin tails, who'd flinch slightly whenever someone caught his gaze. The boy who'd thrown himself without hesitation at Korosensei in his first assassination attempt, a grenade tied to his neck, with no regard whatsoever to how it could have hurt (or fatally wounded) himself. A suicide attempt. He'd remembered how on that day, he lashed out against the students and Nagisa himself, asking him _what on Earth he was thinking. How he'd felt dread in his stomach even after the students went home._

__

__

It worried him, and he'd notice many more incidents after that. 

How the boy appeared to have an unusual amount of bloodlust for someone his age who wasn't raised in such an environment as he had. How he'd tense up from the slightest affection Korosensei would show him such as petting him on the head. The way he was seemingly able to calm someone down with ease when they were angry. another time, he'd noticed several bruises on Nagisa's body, that looked as if someone had grabbed him and slammed him into a wall with considerable force. When asked about them, he said he tripped and hurt himself. 

it wasn't until Korosensei met his mother, Hiromi Shiota, that he felt what it was. he saw how Nagisa acted around her; timid, silent, meek.. He noticed his body language, how his posture was upright, his head bowed. He noticed how his mother talked about him as if her son was not present in the room at all. his heart felt heavy when his mother went on about how Nagisa should have been born as a female and how, when she untied his hair he'd flinch and tremble under the touch of his own mother. Korosensei took to defend him immediately. And then, when she'd yelled at his precious student, calling him nothing but a failure and an embarrassment, that he found his controlled anger begin to well up inside him once more. When the woman stormed out of the room, his gaze fell back on Nagisa. 

Korosensei can’t believe what he just witnessed. _How can someone be so cruel to their child like that?_ He'd finally understood Nagisa's behavior, and it shook him to the core. He turned back to his student then, who was still sitting, hands trembling in his lap. He got up and Korosensei felt himself pulled into a hug. Without hesitation, he'd found his tentacles wrapped around the boy. 

He knew there was little he could do except try and be a positive influence in his life until his deadline, but it filled him with guilt all the same. He'd asked to be a creature who could protect others.. And yet, he couldn't even do that. _Have i failed you, Aguri?_

\------

One night, the human-turned-monster perched upon a building, staring at the crescent moon, when a all-too-familiar scent hit him. _Fear, and something else..?_ His eyes widened in realization when he realized who the scent belonged to. _That's Nagisa. That's Nagisa's scent.._ Worry filled him instantly and he shut his eyes, trying to focus on the direction the scent was coming from. Once he had narrowed down the location, he shot off into the moonlight.

He landed nearby a residential block where the scent was strongest. His ears picked up the sound of a woman yelling, something breaking and the door of a nearby house swinging open. Something inside Korosensei had him straightening against the wall he slumped against and pulled out his phone, sending a quick text to Karasuma just in case. 

He was barely able to take a quick peek as he saw Nagisa appear in the doorway. He wanted to step closer to the blue-haired boy and ask him if he was alright until a taller figure appeared behind him. The child backed away, one hand holding his head as his mother approached. "Mom— Please—"

“Shut the fuck up!” She took a few steps closer to Nagisa. “Why do you exist? Why didn't i convince your father to leave you at the hospital the day you were born, you ungrateful child!” Hiromi spoke, her words searing like venom. 

"I could've had… a great life with a perfect family and a perfect daughter. But you had… To. Ruin. EVERYTHING!" - The woman continued to shout, raising her left hand before backhanding him across the face, sending him backwards, his head colliding with the pavement.

The faint, metallic, and _very familiar_ scent of blood seeped into Korosensei's nostrils then, and he knew he couldn't continue watching when the woman's hand was raised again.

Within a nanosecond he’s away from the wall and between the boy and his failure of a mother. As her hand came down for a second time, Korosensei grabs her wrist with a whip-like tentacle, face blackened. _“Don’t. Touch. Him.”_ He snarled.

It took all of his restraint then and there to stop his barely-contained bloodlust from his days as an assassin from flooding out. He wanted to _kill her, hurt her, make her suffer_ for doing this to his student. 

"I... You! Get out of the way!" Hiromi shouts through tears, continuing to scream as she struggled to break free of Korosensei's tight grip.

She was out of control. No apologies came from her mouth. Only excuses. Nagisa had made eye contact with Korosensei then. He looked terrified, wounds covering his body, crimson blood staining the ground as he watched his mother and invincible teacher fight. 

After a while of keeping Hiromi away from Nagisa in the grasp of his tentacles, Korosensei heard the sound of a car parking in the distance. Karasuma and two other men appeared behind him.

"Step away from the boy." Karasuma commanded, and his two men seized the woman instantly. Releasing his grip, Korosensei rushed to Nagisa's side. Despite his still dark and ferocious appearance, he was careful to be incredibly gentle with him, cradling him in his tentacles. 

The woman stumbles as the two men held her. For a second she looked like she was preparing to fight, but nothing seemed to come of it. “Keep the brat. I never wanted him.” She scoffs and glares at Nagisa, tears streaming down her face, as the men escort her away. 

Karasuma had appeared next to Korosensei then, looking at him and then at Nagisa who was now unconscious in his arms. "What the hell are you doing? Get that kid to the hospital."

\------

Korosensei paces back and forth nervously outside inside the waiting room at the hospital. Karasuma had told him that he wasn't allowed to see Nagisa as his appearance, even in disguise, was too distracting. 

As if on cue, Karasuma and another person he didn't recognize- presumably a doctor, who was clutching a file close to their chest- enters the room. He's on them instantly. 

"How’s- How’s Nagisa-kun? He’s OK, right? He- He’s not severely hurt or anything?" Korosensei hoped and prayed that Nagisa hadn’t been badly hurt. He would never forgive himself if something had happened to him, something he'd promised Aguri would never happen.

Karasuma sighs. "Yes. He's alright. Nothing serious." He pauses and gestures to the woman beside him. "This person would like to ask you a few questions."

The woman glances up and down at Korosensei before beginning to speak. "Hello, i'm Fukui Tsukiko, i'm the social worker assigned to Nagisa Shiota. You're his teacher, correct?" He nodded. "I just need to ask you some questions about him, then you'll be good to go.

\------

After he answered the social worker's questions, he and Karasuma left the hospital and were on their way to the mountain. But an important question nagged at his mind.

"Um, Karasuma-sensei, where will he- Where will Nagisa end up?" Korosensei fiddled nervously at his tie. There was absolutely no way in hell they'd give him back to his mother after what she'd did.

"Well, Octopus, since none of his other family is willing to take him, he's going to end up with a foster family. That is, if they can find someone on such short notice-."

Without thinking, he blurted out, "I wish to adopt Nagisa."

The government agent stopped dead in his tracks and looked at Korosensei with a dumbfounded expression on his face. "I'm afraid you cannot do that."

"Why not?!" Korosensei whined like a child, tentacles flailing.

Karasuma pinched the bridge of his nose and let out a sigh. "Have you forgotten who you are? You're a monster threatening to blow up the planet in less than a year that the government is tasked with killing! _You aren't even a legal citizen!_ He said, frustrated.

"Yes, but--"

"While you promised us that you wouldn't harm any of our students," Karasuma crossed his arms. "You could plan on hurting him while he's in your care. And i'm afraid i won't allow tha-"

Korosensei gently put a tentacle over the man's lips as he interrupted him. "Yes. I may be all of those things, but i would never hurt a child." His gaze softened. "I see some of myself in him. I've never thought about it before, but he feels like a son to me."

Karasuma thought a bit about this. Having the child temporarily live with him could provide more access to Korosensei. Perhaps, through the bond of an adoptive parent, could the young assassin gain more information about the creature's weaknesses. 

It was an interesting idea, but the black haired man was worried about the legal reprocussions. How could he bring this up to his superiors? _How the hell could a monster gain custody?_

"I'll talk to my superiors about it and see what i can do."

Korosensei pounced on him then. "Really?? Thank you, Karasuma-sensei!" He wrapped his tentacles around the disapproving man. Karasuma rolled his eyes. "Yeah, yeah. I'm not doing this for you."

Of all the ways he thought he'd become a father, this was the one Korosensei had least expected.

**Author's Note:**

> After writing my last oneshot for this series i realised there is a severe lack of fics about Koro being the total dad he is. i always kinda saw him as a parental figure to nagisa in the anime and with Nagisas shitty abusive mother that gets mentioned like one episode and then forgotten about, why not let korosensei adopt him??
> 
> note that i don't actually know how the foster system works. oops! its a giant yellow tentacle monster with super speed adopting a kid just roll with it
> 
> I plan to write more chapters of this, thank you for reading!


End file.
